Fabrication of grain boundary junctions using NdFeAs(O,F) superconducting thin films

TL;DR

This paper reports on the growth and analysis of NdFeAs(O,F) superconducting thin films on bicrystal substrates, revealing significant decay in critical current density with grain boundary misorientation, unlike other iron-based superconductors.

Contribution

It demonstrates the epitaxial growth of NdFeAs(O,F) films on MgO bicrystals and investigates their grain boundary transport properties, highlighting differences from other superconductors.

Findings

Critical current density decreases significantly with grain boundary angle.

Fluorine diffusion may weaken grain boundary structure.

Epitaxial growth confirmed by X-ray diffraction.

Abstract

We report on the growth of NdFeAs(O,F) thin films on [001]-tilt MgO bicrystal substrates with misorientation angle theta_GB=6{\deg}, 12{\deg}, 24{\deg} and 45{\deg}, and their inter- and intra-grain transport properties. X-ray diffraction study confirmed that all our NdFeAs(O,F) films are epitaxially grown on the MgO bicrystals. The theta_GB dependence of the inter-grain critical current density Jc shows that, unlike Co-doped BaFe2As2 and Fe(Se,Te), its decay with theta_GB is rather significant. As a possible reason of this result, fluorine may have diffused preferentially to the grain boundary region and eroded the crystal structure.